1. Field of the Invention
The present invention relates to a precision method of short-term relining, constructing or reconstructing a blast furnace. Particularly, the method realizes significant shortening and simplification of the relining or construction process and reduction in cost.
2. Description of the Related Art
Conventionally, relining of a blast furnace is carried out by successively disassembling the blast furnace from top to bottom and thereafter successively assembling the blast furnace from the bottom to the top in reverse. In the disassembling and assembling operation, a furnace top crane is installed in the vicinity of the top of the blast furnace. However, the lifting capacity of the usual furnace top crane is only about 60 through 100 tons. Therefore, the disassembling and assembling operation requires dividing the blast furnace (hereinafter referred to as "shell") and its firebricks into a number of small units. Further, a time period as long as 120 to 150 days is required to complete relining. Further, work at a high elevation in the furnace is needed, posing a problem of safety. This is also a problem in newly constructing a blast furnace.
Japanese Patent Publication No. 39322/1978 proposes a method in which a blast furnace is divided into several sections or blocks extending from a furnace top portion to a furnace bottom portion, the divided blocks are successively assembled from the furnace top portion to the furnace bottom portion by the so-called "lift-up" method, and finally the furnace bottom portion is fixed onto a foundation of the blast furnace along with a furnace bottom base plate. Further, the respective divided blocks are preconstructed at a location other than the foundation of the blast furnace. Further, the assembling operation is carried out by utilizing an attached framework for constructing the blast furnace installed above the furnace tower.
Japanese Patent Publication No. 43404/1985 proposes a method in which a projected deck is attached to a furnace framework installed above the blast furnace tower, and a forwardly and rearwardly movable carriage is arranged on the deck. In the disassembling operation, the blast furnace is divided into several ring-like blocks from a furnace top portion to a furnace bottom portion. Blocks above the projected deck are moved out of the furnace by utilizing the carriage while successively conveying them down. Meanwhile, blocks below the deck are moved out of the furnace similarly by the carriage while successively conveying them up. Further, in relining the blast furnace is assembled by similarly utilizing the carriage on the projected deck in reverse of the disassembling procedure. This is a so-called "center drawing" method.
Japanese Patent Laid-Open No. 87907/1978 proposes a method of utilizing an operation floor installed at a furnace framework above the furnace tower similar to Japanese Patent Publication No. 43404/1985. In disassembling, portions above a tuyere portion are moved out of the furnace by utilizing a carriage while successively conveying them down. Meanwhile, portions below the tuyere portion are disassembled separately by bulldozers or the like. Further, in relining of the blast furnace, the portions below the tuyere portion are installed by conveying them down from the operation floor and portions above the tuyere portion are bonded while successively conveying them up. However, in this case, the assembling operation is carried out only in respect of the shell.
In all of the above-described conventional methods, no consideration is given to the delicacy of the complicated integral sections that comprise the shell, the brittle firebrick and the structure for maintaining the firebrick in place, or the warping or strain imposed upon the firebrick portions, or to the danger of deformation of the shell, which is caused by newly moving, assembling and placing the heavy divided blast furnace segments. Therefore, cracks are caused at bond portions of laid bricks owing to warping or strain or deformation of the shell in the moving and assembling operation. When the warping or the like is considerable, laid bricks tend to collapse. Further, there are problems of malfunction or destruction of attached measuring instruments and piping, and failure in bonding the separate integral blast furnace segments, which are sometimes called "ring-like blocks," or simply "blocks."
In the apparatus of Japanese Patent Publication No. 39322/1978, a problem is presented in which a jacking-up operation by hydraulic jacks installed at a furnace bottom base plate is indispensable in assembling or moving the furnace bottom. This requires the equipment and the operation to be complicated.
Further, according to Japanese Patent Publication No. 43404/1985 and Japanese Patent Laid-Open No. 87907/1978, the respective sections or blocks need to be removed and carried by utilizing the operation floor installed at the furnace framework above the furnace tower. Therefore, the operation is complicated and the investment cost is increased.
The applicants have previously developed a method of short-term relining or construction of a blast furnace capable of resolving the above-described problems, and have disclosed the method in Japanese Patent Laid-Open No. 143521/1997. Therein the occurrence of warping or straining of brickwork portions is effectively prevented, and roundness is essentially ensured in moving and assembling divided blocks. In this method, there is no need of jacking-up in moving and assembling the furnace bottom; all of the respective blocks are moved and hung up at the furnace foundation level and no operation floor or crane is needed. The existing furnace is disassembled and another blast furnace is reconstructed on the foundation thereof, or a A totally new blast furnace is constructed. The method comprises the following steps:
1. The furnace is divided into several ring-like blocks from the furnace top portion to the furnace bottom portion.
2. The blocks are constructed at a location other than the foundation of the blast furnace.
3. Blocks other than the furnace bottom block are provided with means for preventing warping or straining of the brickwork portions and means for deforming the shell.
4. In respect of the furnace bottom block, bricks are laid on a furnace bottom plate installed at a lower end thereof.
5. Blocks other than the furnace bottom block are moved onto the foundation of the blast furnace by horizontal transfer.
6. Blocks other than the furnace bottom block moved onto the foundation of the blast furnace, are successively lifted up from the furnace top portion by the lift-up method and are bonded together to thereby constitute upper blocks.
7. The furnace bottom block is moved and installed onto the foundation by horizontal transfer at the blast furnace foundation level.
8. The furnace bottom block and the upper blocks are bonded together.
Occurrence of warping or straining at brickwork portions in moving, hanging up and bonding, can effectively be prevented. Further, the roundness of the furnace can substantially be ensured. Further, in assembling the respective blocks, when the entire brick-layers, electric instrumentation, piping, drying of the bricks and coating of the equipment and other steps are carried out, the relining or construction term can significantly be shortened to about 70 to 90 days. That is, simplification of relining or construction operation, as well as reduction in relining or construction cost, can be achieved.
Integrated iron and steel works, in recent times, tend to provide a production system in which extra facilities are not provided and the operational rate of aggregated facilities is promoted. Therefore, in blast furnaces which are limited to one or two furnaces in the entire iron and steel works, further shortening of the relining or the construction period is desired. However, according to the above-described methods, further shortening of this period is difficult to achieve. Many related facilities are installed around a blast furnace, and this becomes a troublesome and time-consuming operation in which existing attached facilities need to be temporarily removed and later installed again. That is, according to the relining and constructing methods disclosed previously, particularly in relining a blast furnace, a problem arises in which heavy integrated blast furnace segments cannot often be moved safely and smoothly onto a foundation of a blast furnace.